Encoded optical element of a laser processing head

ABSTRACT

A device for a laser processing head includes an optical element configured for attachment to the laser processing head, a housing for the laser processing head configured to receive the optical element, and a mechanical encoding disposed on at least one of the optical element and the housing to permit installation of a predetermined optical element at a predetermined orientation into the housing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to European Patent Application EP04024921, filed on Oct. 20, 2004, the entire contents of which arehereby incorporated by reference.

TECHNICAL FIELD

This application relates to optical elements of a laser processing head.

BACKGROUND

Generally, it is difficult and/or impractical to visually distinguishthe mirror surfaces of non-planar mirrors such as deflecting mirrors orfocusing mirrors of a laser processing head. Unambiguous features of themirrors can include the material number or labeling. This labeling isapplied in a separate working process which bears a very high risk ofconfusion. To ensure optically correct function, the installationposition and orientation of the mirror should be defined. Despite thelabeling, mounting errors are possible.

SUMMARY

According to one general aspect, an optical element of a laserprocessing head is configured to disallow installation of the opticalelement to the processing head in other than in permissibleorientations. In some embodiments, an optical element includes amechanical encoding disposed on either the optical element, the housingor both the optical element and the housing to permit installation of apredetermined optical element at a predetermined orientation into thehousing. The mechanical encoding provides unambiguous identification ofthe optical element. The location of installation of the opticalelement, a mirror for example, on the laser processing head isconfigured such that only the correct optical element can be installedin the correct installation position. The removal of mirrors forcleaning or sending spare parts to customers, for example, can behandled even by less qualified staff without the risk of confusionbetween disparate optical elements having a similar appearance. Thisconfiguration preserves the function of the optical configuration andminimizes the danger of destruction of bordering components due improperinstallation of optical elements. A laser cutting head housing would,for example, be destroyed by installing a mirror with excessive focallength.

The mechanical encoding can include at least one profile and at leastone complementary recess which cooperates with the profile. In someembodiments, the mechanical encoding includes a profile on the opticalelement, which may be in the form of teeth, projections, curvatures orelevations or the like which can be inserted into a correspondingdepression or recess of the laser processing head. In some embodiments,the mechanical encoding includes a profile, such as a depression and/orrecess, for example, on the optical element and/or on the laserprocessing head.

In some embodiments, the optical element includes threaded holes intowhich threaded pins can be screwed. This design permits to select andquickly implement the encoding (number and position of the pins). Insome embodiments, the encoding is made permanent by gluing in thethreaded pins.

Various embodiments are suited for a plurality of components of a laserprocessing head, such as mirrors, for example, on which the encoding maybe applied as follows: The mirror is mounted to a carrier to be mountedto the housing of the laser processing head which includes themechanical encoding.

Other features will be apparent from the description, the drawings andthe claims.

DESCRIPTION OF DRAWINGS

FIG. 1 shows a perspective top view of a laser cutting system;

FIG. 2 shows a longitudinal section of parts of the laser cutting headof the laser cutting system;

FIG. 3 a shows a top view of a mirror of the laser cutting head;

FIG. 3 b shows a side view of the mirror of the laser cutting head;

FIG. 3 c shows a section through IIIc-IlIc of FIG. 3 a of the mirror ofthe laser cutting head; and

FIG. 3 d shows a perspective view of the mirror of the laser cuttinghead.

DETAILED DESCRIPTION

FIG. 1 shows the construction of a laser cutting system 1 for lasercutting using a CO₂ laser 2, a laser processing head 4 and a workpiecesupport 5. A generated laser beam 6 is guided by means of deflectingmirrors to the laser processing head 4 and is directed onto a workpiece8 using mirrors. In some examples, the workpiece is sheet metal.

The laser beam 6 must penetrate through the workpiece 8 to produce acontinuous kerf. The workpiece 8 must be spot-wise melted or oxidized atone location and the molten mass must be blown out. The piercing processcan be performed rapidly (i.e. with full laser power) or slowly (via aso-called “ramp”).

In case of slow piercing of the workpiece 8 with a ramp, the laser powercan be gradually increased, reduced and be kept constant over a certainperiod until the pierced hole is generated. Piercing and also lasercutting are supported by adding a gas. Oxygen, nitrogen, pressurized airand/or application-specific gases can be used as cutting gases 9. Whichgas is eventually used depends on the materials to be cut and on therequired quality of the workpiece 8.

Cutting with oxygen is usually performed using a gas pressure ofmaximally 6 bars. The material is molten and largely oxidized at thelocation where the laser beam 6 meets the workpiece 8. The producedmolten mass is blown out together with the iron oxides. The particlesand gases produced can be suctioned out of a suction chamber 11 using asuction means 10. During oxidation (exothermal reaction) additionalenergy is released which promotes the cutting process. If oxygen is usedas cutting gas for a material thickness which permits use of the samelaser power for oxygen cutting as well as nitrogen high-pressurecutting, the processing cutting speeds may be considerably higher or thematerial thickness to be cut may be larger compared to nitrogen.

In accordance with FIG. 2, a deflecting mirror 12 and a focusing mirror13 are provided to direct the laser beam 6 onto the workpiece. It ispossible to produce a gas jet coaxially to the laser beam 6 using anannular gap nozzle without requiring a transmissive element as a sealingelement to build up pressure. The two mirrors 12 and 13 are inserted inreceptacles of a housing 16 in the direction of arrows 14 and 15,respectively. The two mirrors 12 and 13 of FIG. 2 are depicteddifferently in order to clearly show their function. In someembodiments, the mirrors 12 and 13 are almost identical, with only theirmirror surfaces 17 and 18 being different. The two mirrors aremechanically encoded for differentiation, which is explained withreference to the example of the deflecting mirror 12.

In accordance with FIGS. 3 a through 3 d, the deflecting mirror 12 ismounted to a carrier 19 which is inserted into the receptacle of thehousing 16 of the laser cutting head 4. The carrier 19 can be mounted tothe housing via bores 20. The carrier 19 comprises additional threadedholes 21 to 24 into which threaded pins 25 can be inserted and gluedsuch that the threaded pins project beyond the carrier 19 and protrudeover its carrier surface 26. The mechanical encoding consists of thenumber and position of the threaded pins. The receptacle on the lasercutting head has at least one depression for inserting a threaded pin incorrespondence with the encoding. In some examples, encoding may beprovided by inserting threaded pins into the bores 21, 22 and 24 andproviding three corresponding depressions on the housing of the lasercutting head.

1. A device for a laser processing head, the device comprising: anoptical element configured for attachment to the laser processing head;a housing for the laser processing head configured to receive theoptical element; and a mechanical encoding disposed on at least one ofthe optical element and the housing to preset an admissible installationof the optical element into the housing.
 2. The device according toclaim 1, wherein the housing comprises a recess and the optical elementcomprises a profile which can be inserted into the corresponding recessof the housing when the optical element is installed.
 3. The deviceaccording to claim 1, wherein the optical element comprises a recess andthe housing comprises a profile which can be inserted into thecorresponding recess of the optical element when the optical element isinstalled.
 4. The device according to claim 1, wherein the opticalelement comprises holes configured to receive pins.
 5. The deviceaccording to claim 4, wherein the pins are threadably connected to theholes in the optical element.
 6. The device according to claim 4,wherein the pins are connected to the holes with an adhesive.
 7. Thedevice according to claim 1, wherein the optical element comprises amirror.
 8. The device according to claim 1, wherein the mechanicalencoding comprises at least one of teeth, curvatures and elevationssized and configured to be received in a corresponding recess.
 9. Adevice for a laser processing head, the device comprising: a housing forthe laser processing head; an optical element configured forinstallation on the housing; and a mechanical encoding disposed on thehousing to limit the installed orientation of the optical element on thehousing.
 10. The device according to claim 9, further comprising acarrier to support the optical element, the carrier being mounted to thehousing of the laser processing head.
 11. The device according to claim9, wherein the housing comprises a recess and the optical elementcomprises a profile which can be inserted into the corresponding recessof the housing.
 12. The device according to claim 9, wherein the opticalelement comprises a recess and the housing comprises a profile which canbe inserted into the corresponding recess of the optical element. 13.The device according to claim 9, wherein the optical element comprisesholes configured to receive pins.
 14. The device according to claim 13,wherein the pins are threadably connected to the holes.
 15. The deviceaccording to claim 10, further comprising a plurality of pins attachedto the carrier in predetermined positioned corresponding to a pluralityof predetermined recesses in the housing, such that the carrier isattachable to the housing in only a single permissible orientation. 16.The device according to claim 15, wherein the carrier is attachable tothe housing in a plurality of permissible orientations.
 17. The deviceaccording to claim 9, wherein the mechanical encoding comprises at leastone of teeth, curvatures and elevations which are sized and configuredto be received in a corresponding recess on the optical element.
 18. Adevice for a laser processing head, the device comprising: a housing forthe laser processing head; first and second optical elements configuredfor attachment to the housing; and a first mechanical encoding disposedproximate an opening in the housing and configured to permitinstallation of the first optical element in a predetermined orientationand to disallow installation of the second optical element.
 19. Thedevice according to claim 18, further comprising a second mechanicalencoding disposed proximate an opening in the housing and configured topermit installation of the second optical element in a predeterminedorientation and to disallow installation of the first optical element.20. A method for installing an optical element in a designated position,the method comprising: providing an optical element configured forattachment to the laser processing head, a housing for the laserprocessing head configured to receive the optical element; and amechanical encoding disposed on at least one of the optical element andthe housing to permit at least one predetermined orientation of theoptical element when inserted into the housing; aligning the opticalelement into a predetermined orientation of the mechanical encoding; andinserting the optical element into the housing of the laser processinghead.